Seal block device for use in oil hydraulic gear pump

ABSTRACT

A seal block device for use in an oil hydraulic gear pump is provided which comprises a seal block adapted to be interposed between the inner peripheral surface of a pump casing near an oil outlet port of the pump and drive and driven gears which are so provided within the pump casing as to mesh with each other. A first communicating means communicates with a pressure receiving chamber formed by the side of the drive gear in the outer peripheral surface of the seal block and a space defined by and between the driven gear and a seal face of the seal block facing the driven gear, and a second communicating means for communicating with another pressure receiving chamber formed by the side of the driven gear in the outer peripheral surface of the seal block and a space defined by and between the drive gear and another seal face of the seal block facing the drive gear.

United States Patent [191 Kitta et al.

[ 1 Oct. 28, 1975 SEAL BLOCK DEVICE FOR USE IN OIL HYDRAULIC GEAR PUMP [75] Inventors: Yasuo Kitta; Sumio Sugahara, both of Yokohama, Japan [73] Assignee: Kabushiki Kaisha Komatsu Seisakusho, Tokyo, Japan [22] Filed: Apr. 17, 1974 [21] Appl. No.: 461,794

[30] Foreign Application Priority Data Primary Examiner-John .l. Vrablik Attorney, Agent, or Firm-Armstrong, Nikaido & Wegner [5 7] ABSTRACT A seal block device for use in an oil hydraulic gear pump is provided which comprises a seal block adapted to be interposed between the inner peripheral surface of a pump casing near an oil outlet port of the pump and drive and driven gears which are so provided within the pump casing as to mesh with each other. A first communicating means communicates with a pressure receiving chamber formed by the side of the drive gear in the outer peripheral surface of the seal block and a space defined by and between the driven gear and a seal face of the seal block facing the driven gear, and a second communicating means for communicating with another pressure receiving chamber formed by the side of the driven gear in the outer peripheral surface of the seal block and a space defined by and between the drive gear and another seal face of the seal block facing the drive gear.

3 Claims, 6 Drawing Figures US. Patent Oct. 28, 1975 FIG. 4

FIG. 3

FIG. 6

FIG. 5

SEAL BLOCK DEVICE FOR USE IN OIL HYDRAULIC GEAR PUMP BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a seal block device for use in an oil hydraulic gear pump, and more particularly to a seal block device by which the seal block is prevented from the phenomenon of one-sided contact with drive and driven gears.

2. Description of the Prior Art In the recent years, a high pressure oil hydraulic gear pump has been developed with a seal block adapted to be interposed between the inner peripheral surface of a pump casing near the oil outlet port of the pump and drive and driven gears, which are provided within the pump casing to mesh with each other and to be rotatable. This type of gear pump was developed in view of the fact that there has been a fear that a phenomenon called scuffing might occur in the inner peripheral surface of the pump casing. This is caused by the peaks of the gears coming into contact with the inner peripheral surface of the pump casing and peaks of the gears due to a large load applied to gear shafts of the gears, eccentricity of the gears caused by an increase in clearance between the respective shafts and bearings, and heat expansion of the gears. It has, however, been unavoidable in the above described conventional gear pump that, when the seal block is moved upwards or downwards within the pump casing because of vibration, etc. the seal block per se is brought into one-sided contact with the gears so that an abnormal wear occurs in the seal face of the seal block which may be kept in sliding contact with the gears, and further the volumetric efficiency of the gear pump itself is reduced.

SUMMARY OF THE INVENTION The present invention is intended to eliminate the above described disadvantages of the conventional seal block device for use in an oil hydraulic gear pump.

It is therefore a primary object of the present invention to provide an improved seal block device for use in an oil hydraulic gear pump which can restore onesided contact of the drive and driven gears of the pump to normal sliding contact.

It is another object of the present invention to provide an improved seal block device for use in an oil hydraulic gear pump which can prevent abnormal wear of a seal face of the seal block.

It is further object of the present invention to provide an improved seal block device for use in an oil hydraulic gear pump which can prevent reduction of the volumetric efficiency of the pump.

In order to achieve the above described objects, the seal block device for use in an oil hydraulic gear pump according to the present invention comprises a seal block adapted to be interposed between the inner peripheral surface of a pump casing near the oil outlet port of the pump and drive and driven gears which are so provided within the pump casing as to mesh with each other. A first communicates means for communicating with a pressure receiving chamber formed by the side of the drive gear in the outer peripheral surface of the seal block and a space defined by and between the driven gear and a seal face formed by the side of the driven gear on the inner surface of the seal block and having a circular arc shape in its cross section. A second communicating means communicates with another pressure receiving chamber formed by the side of the driven gear in the outer peripheral surface of the seal block and a space defined by and between the drive gear and another seal face formed by the side of the drive gear on the inner surface: of the seal block and having a circular arc shape in its cross section.

Further, the above described seal block device according to the present invention is so constructed that the distance between the respective circular arc centers of the seal faces is equal to or shorter than the distance between the longitudinal axes of the shafts of the drive and driven gears.

Still further, the above described first communicating means consists of a conduit hole formed within the seal block, one end thereof opening into the pressure receiving chamber formed by the side of the drive gear, and another conduit hole formed within a side plate of the gear pump so as to communicate with the conduit hole formed within the seal block, one end thereof opening into the spaced defined by and between the driven gear and the seal face formed by the side of the driven gear on the inner surface: of the seal block, and the above described second communicating means consists of a conduit hole formed within the seal block, one end thereof opening into the pressure receiving chamber formed by the side of the driven gear, and another conduit hole formed within another side plate of the pump so as to communicate with the conduit hole formed within the seal block, one end thereof opening into the space defined by and between the drive gear and the seal face formed by the side of the drive gear on the inner surface of the seal block.

BRIEF EXPLANATION OF THE DRAWINGS These and other objects, features and advantages of the present invention will become apparent from the following description taken in conjunction with accompanying drawings in which:

FIG. 1 is an explanatory view of the structure of a seal block device according to one embodiment of the present invention provided in an oil hydraulic gear P p FIG. 2 is a sectional view of the device taken along line II-II in FIG. 1,

FIG. 3 is a front view of a seal block interposed between side housings,

FIG. 4 is a view for explaining the function of the seal block device according to the present invention,

FIG. 5 is a view for explaining another example of seal block device, and

FIG. 6 is a view for explaining the function of the seal block device shown in FIG. 5.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIGS. 1 to 3, numeral 1 represents a center housing for a casing of an oil hydraulic gear pump. The casing consists of the center housing 1 and cable plates 14 and 15 which are located on the opposite sides thereof and is provided with an inlet port 2 and an outlet port 3 for oil. The casing houses therein a drive gear 4 and a driven gear 5 which are meshed with each other. Between the drive gear 4, the driven gear 5 and the inner peripheral surface of the casing near by the outlet port 3, a seal block 6 is interposed.

In the outer surface of the seal block 6, a pressure receiving chamber 7 is formed at the central portion thereof, a pressure receiving chamber 8 is formed by the side of the drive gear 4 and a pressure receiving chamber 9 isformed by the side of the drive gear 5 wherein the pressure receiving chambers 8 and 9 are located on the opposite sides to each other. The pressure receiving chamber 7 is provided with an oil outlet port 10a. Inthe inner surface of the seal block 6, there are provided a seal face 10 formed by the side of the drive gear 4, having a circular arc shape in its cross section and a seal face 11 formed by the side of the driven gear 5, having a circular arc shape in its cross section also. Within the seal block 6, there are provided conduit holes 12 and 13. One end of the conduit hole 12 opens into the pressure receiving chamber 9, and the other end thereof opens into the side face 6a of the seal block 6. (on the right side of the seal block in FIG. 3) While, one end of the conduit hole 13 opens into the pressure receiving chamber 8 and the other end thereof opens into the other side face 6b of the seal block 6. (on the left side of the seal block 6 in FIG. 3)

Within the side plates 14 and 15 in which the drive and driven gears 4, 5 are rotated in sliding contact therewith, there are provided conduit holes 16 and 17, respectively. One end of the conduit hole 16 opens into the inner face of the side housing 14 so as to communicate with the conduit hole 12 formed within the seal block 6, and the other end thereof opens into a space 4a defined by and between the seal face 10 and the drive gear 4, which is rotated in a sliding contact therewith, such as tooth grooves of the drive gear 4. While, one end of the conduit hole 17 opens into the inner face of the side housing 15 so as to communicate with the conduit hole 13 formed within the seal block 6, and the other end thereof opens into a space 5a, such as tooth grooves of the driven gear 5, defined by and between the seal face 11 and the driven gear 5 which is rotated in a sliding contact therewith.

In thus constructed seal block device according to the present invention, when the seal block 6 is moved upwards because of vibration, etc., so that the end A of the seal face 10 formed by the side of the drive gear 4 on the inner surface of the seal block 6 is brought into one-sided contact with the edge of the drive gear 4, the end B of the seal face 11 formed by the side of the driven gear 5 on the inner surface of the seal block 6 is brought into one-sided contact with the edge of the driven gear 5, a space which is defined by and between the drive gear 4 and the seal face 10 is subjected to a low pressure P,, while a space F which is defined by and among the drive gear 4, the driven gear 5 and the seal face 11 is subjected to a high pressure P because the space F is sealed by the ends A and B. The low pressure P acts on the pressure receiving chamber 9 formed by the side of the driven gear 5 through the conduit holes 16 and 12, while the high pressure P exerts on the pressure receiving chamber 8 formed by the side of the drive gear 4 on the inner surface of the seal block 6 through the conduit holes 17 and 13. As a result, the

pressure P exerted on the pressure receiving chamber 8 becomes higher than the pressure P, exerted on the pressure receiving chamber 9, so that the seal block 6 is moved downwards by the action of the pressure P acting on the pressure receiving chamber 8 and is brought again into a normal sliding contact with the gears 4 and 5 in its normal position within the casing of the pump.

In the above described seal block device according to the present invention, it is, further, so arranged that the distance L (GIG between the respective centers 0 and 0 of the circular arcs of the seal faces 10 and 11 is equal to or shorter than the distance L, (TL (T between the respective longitudinal axes O and O of the drive and driven gears 4 and 5. The reason for this will be clear from the following description taken in reference to FIGS. 5 and 6.

In one example as shown in FIG. 5, there is provided a seal block 6 in which the distance L (0 0 between the respective centers O', and 0' of the circular arcs of the seal faces 10' and 11 is longer than the distance L (O' O between the respective longitudinal axes O, and 0' of the drive and driven gears 4 and 5. In this case, the seal block 6' is brought into one-sided contact with the drive gear 4 and the driven gear 5, re spectively, at the ends A and B of the seal block 6 as shown in FIG. 6, so that both a space defined by and between the seal face 10 and the drive gear 4 and a space defined by and between the seal face 11 and the driven gear 5 are subjected to a low pressure, and a high pressure space F is defined by the drive gear 4, the driven gear 5 and a portion of the seal block 6. The oil outlet port 10a is formed in the space F and is sealed by the ends A and B of the seal block 6 and does not communicate with any of the above described conduit holes. As a result, such restoring force as described above is not exerted on the seal block 6', so that the one-sided contact condition of the seal block 6' to the drive gear 4 and driven gear 5 can not be rectified.

As clear from the foregoing description, according to the seal block device of the present invention, it is possible to provide the seal block with a restoring force which enables it to restore to its normal position whenever the seal block is brought into one-sided contact with the drive and driven gears.

Thus, it is possible in the oil hydraulic gear pump having the seal block device according to the present invention to prevent abnormal wear of the seal faces of the seal block and reduction of volumetric efi'iciency of the oil hydraulic gear pump.

What is claimed is:

1. In a seal block device for use in an oil hydraulic gear pump including a seal block positioned between the inner peripheral surface of a casing of the pump and a drive and a driven meshing gears positioned within a portion of the casing, the improvement comprising a first communicating means for communicating only with a pressure receiving chamber formed on the side of said drive gear on the outer peripheral surface of said seal block and a space between said driven gear and a seal face formed on the side of said driven gear on the inner surface of said seal block having a circular arc shape in its cross section, and a second communicating means for communicating only with another pressure receiving chamber formed on the side of said driven gear on the outer peripheral surface of said block and a space between said drive gear and a seal face formed on the side of said drive gear on the inner surface of said seal block and having a circular arc shape in its cross section. r

2. The seal block device as set forth in claim 1, wherein the distance between the respective centers of said circular arcs of said seal faces is equal to or less than the distance between the respective longitudinal axes of shafts of said drive and driven gears.

3. The seal block device as set forth in claim 1 wherein said first communicating means comprises a first conduit hole formed within said seal block, one end thereof opening into said pressure receiving chamber formed by the side of said drive gear andthe other end opening into a side face of said seal block, and a second conduit hole formed within a first side plate of said pump, one end thereof opening into the inner face of said first side housing so as to communicate with said first conduit hole and the other end opening into said space between said driven gear and said seal face which are slidingly contacted with each other, and wherein said second communicating means comprises a third conduit hole formed within said seal block, one end thereof opening into said pressure receiving chamber formed by the side of said driven gear and the other end opening into another side face of said seal block, and a fourth conduit hole formed within a second side plate of said pump, one end thereof opening into the inner face of said second side housing as to communicate with said third conduit hole and the other end opening into said space between said drive gear and said seal face of the seal block which are slidingly contacted with each other. 

1. In a seal block device for use in an oil hydraulic gear pump including a seal block positioned between the inner peripheral surface of a casing of the pump and a drive and a driven meshing gears positioned within a portion of the casing, the improvement comprising a first communicating means for communicating only with a pressure receiving chamber formed on the side of said drive gear on the outer peripheral surface of said seal block and a space between said driven gear and a seal face formed on the side of said driven gear on the inner surface of said seal block having a circular arc shape in its cross section, and a second communicating means for communicating only with another pressure receiving chamber formed on the side of said driven gear on the outer peripheral surface of said block and a space between said drive gear and a seal face formed on the side of said drive gear on the inner surface of said seal block and having a circular arc shape in its cross section.
 2. The seal block device as set forth in claim 1, wherein the distance between the respective centers of said circular arcs of said seal faces is equal to or less than the distance between the respective longitudinal axes of shafts of said drive and driven gears.
 3. The seal block device as set forth in claim 1 wherein said first communicating means comprises a first conduit hole formed within said seal block, one end thereof opening into said pressure receiving chamber formed by the side of said drive gear and the other end opening into a side face of said seal block, and a second conduit hole formed within a first side plate of said pump, one end thereof opening into the inner face of said first side housing so as to communicate with said first conduit hole and the other end opening into said space between said driven gear and said seal face which are slidingly contacted with each other, and wherein said secOnd communicating means comprises a third conduit hole formed within said seal block, one end thereof opening into said pressure receiving chamber formed by the side of said driven gear and the other end opening into another side face of said seal block, and a fourth conduit hole formed within a second side plate of said pump, one end thereof opening into the inner face of said second side housing as to communicate with said third conduit hole and the other end opening into said space between said drive gear and said seal face of the seal block which are slidingly contacted with each other. 